Date of Graduation

5-2023

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Food Science (PhD)

Degree Level

Graduate

Department

Food Science

Advisor/Mentor

Wang, Ya-Jane

Committee Member

Lee, Sun-Ok

Second Committee Member

Thallapuranam, Suresh

Third Committee Member

Ubeyitogullari, Ali

Fourth Committee Member

Qian, Xianghong

Keywords

Chemical modification; Delivery system; Enzyme; Physical modification; Porous; Starch

Abstract

Porous starch produced by enzyme hydrolysis has attracted much attention for its adsorption and delivery properties. Porous starch has been successfully prepared from A-type starch, but not from B-type and C-type starches, which is partly attributed to the surface and crystalline structure. The present study aimed to characterize the role of the crystalline structure and the structure-function relationship impacting the susceptibility of starch with different crystalline polymorphs to amylase digestion. The starches were subjected to chemical modification (acid hydrolysis or surface gelatinization), physical modification (heat-moisture treatment, HMT, or high-pressure processing, HPP) or their combinations prior to amylase digestion, and the physiochemical properties of the resultant starches were characterized. Both acid hydrolysis and surface gelatinization removed densely packed crystallites to improve amylase binding and the digestion degree, resulting in the formation of a porous structure in potato starch. Combined acid hydrolysis and HMT reduced the amylase digestion degree of all three starches by increasing their thermal stability and crystallinity from hydrolyzed starch chains that reorganized into more thermally stable structures. The strong electrostatic interaction of sodium sulfate with water molecules decreased the gelatinization degree during HPP, and generally decreased the α-amylase digestion degree compared to HPP in water for all three starches. However, the competition for the water in the starch crystallites and the restricted association of gelatinized starch from reduced free water in sodium sulfate allowed the formation a porous structure in corn and potato starches and their partial transition to a C-like polymorph. The results demonstrate that the combination of chemical or physical modification and alpha-amylase digestion was capable of producing porous starch from B-type starches. This study will help develop porous starch with new properties for applications in food, pharmaceutical and agricultural industries.

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